Hong Chen's research while affiliated with Shanghai Research Institute of Sports Science and other places

5F‐MDMB‐PICA, an indole‐type synthetic cannabinoid (SC), was classified illicit globally in 2020. Although the extensive metabolism of 5F‐MDMB‐PICA in the human body warrants the development of robust analytical methods for metabolite detection and quantification, a current lack of reference standards for characteristic metabolites hinders such method creation. This work described the synthesis of 18 reference standards for 5F‐MDMB‐PICA and its possible Phase I metabolites, including three hydroxylated positional isomers R14 to R16 . All the compounds were systematic characterized via nuclear magnetic resonance, Fourier transform infrared spectroscopy, and high‐resolution mass spectrometry. Furthermore, two methods were developed for the simultaneous detection of all standards using liquid chromatography–tandem mass spectrometry and ultra‐performance liquid chromatography–quadrupole time‐of‐flight mass spectrometry. By comparison with authentic samples, R17 was identified as a suitable urine biomarker for 5F‐MDMB‐PICA uptake.

In this study, a novel material of core–shell structured magnetic molecularly imprinted polymers (Fe 3 O 4 @SiO 2 @Au (FSA)-MIPs) was successfully prepared for the rapid and selective determination of 4-methylmethcathinone (mephedrone, 4-MMC). The adsorption capacity of FSA-MIPs is 34.7 mg·g ⁻¹ at 308 K, which is significantly higher than magnetic non-imprinted polymers profiting from the imprinting effect. The FSA-MIPs have a short equilibrium (20 min) and could be reused more than six times. Moreover, the selectivity coefficients of FSA-MIPs for 4-MMC, 3,4-dimethylmethcathinone, butylone, 4-ethylmethcathinone, acetylfentanyl, and methylene blue are 4.01, 5.65, 7.62, 12.30, and 20.87 respectively, further indicating the markedly enhanced binding selectivity of FSA-MIPs. As an adsorbent, the FSA-MIPs were successfully applied for effective extraction of 4-MMC in three human urine samples with the recovery rates ranging from 85.5–92.6%. The results confirmed that the FSA-MIPs have good prospects in the extraction and separation of synthetic cathinones, which is suitable for further application in the criminal sciences field.

A programmed, autonomous, and self-powered DNA motor was developed for one-step amplification detection of ochratoxin A (OTA). The OTA can bind with the aptamer of hairpin and induce the opening of hairpin. Then, the Mg2+-specific DNAzyme can circularly cleave the fluorophore-labeled DNA on the gold nanoparticles (AuNPs), causing autonomous and processive movement of DNA motor. Finally, the cleaved fluorophore-labeled DNA segments can leave from the AuNP surface, causing significant recovery of fluorescent signal. A good linear range was obtained from 0.01 to 5 nM (R2 = 0.992) with a detection limit of 2 pM. Importantly, this strategy is self-powered and only one-step operation is needed for the whole process. It shows great potential in food security supervision or biological imaging of OTA.

As a kind of new psychoactive substance (NPS), synthetic cathinones have drawn great worldwide attention. In this study, molecularly imprinted polymers (MIPs), as adsorbents for the extraction and determination of 4-methyldimethcathinone (4-MDMC), were first synthesized by coprecipitation polymerization. The physicochemical analyses of MIPs were successfully performed by XRD, FTIR, FESEM and TGA techniques. Furthermore, rebinding properties of temperature and pH dependence, and selectivity and reusability tests for MIPs and non-imprinted polymers (NIPs) were performed using an ultraviolet-visible spectrometer (UV-vis). The obtained results indicate that the imprinting efficiency has strong dependence on temperature and pH, and the optimal adsorption for targets is achieved under the condition of 318 K and pH = 6.0. This means that the combination between the polymers and 4-MDMC is a strong spontaneous and endothermic process. Compared with NIPs, MIPs exhibit prominent adsorption capacity (Qe= 9.77 mg g⁻¹, 318 K). The selectivity coefficients (k) of MIPs for 4-MDMC, methylenedioxypentedrone (βk-MBDP), 4-ethylmethcathinone (4-EMC), methoxetamine (MXE) and tetrahydrofuranylfentanyl (THF-F) were found to be 1.70, 3.49, 7.14 and 5.82, respectively. Moreover, it was found that the adsorption equilibrium was achieved within 30 min. The aim of this work is the simple synthesis of MIPs and the optimal performance of the molecular recognition of 4-MDMC. Moreover, the synthesized MIPs can be easily regenerated and repeatedly used with negligible loss of efficiency (only 9.94% loss after six times adsorption-desorption tests). Satisfying recoveries in the range of 69.3-78.9% indicate that MIPs have good applicability for analyte removal from urine samples. Ultimately, this material shows great promise for the rapid extraction and separation of synthetic cathinones, which are dissolved in the liquid for the field of criminal sciences.

An entropy driven catalytic reaction powered DNA motor was proposed for simultaneous detection of ochratoxin A (OTA) and chloramphenicol (CAP) in food. The dumbbell hairpin structure was formed by the two aptamers of OTA and CAP. The dumbbell hairpin can be opened by the interaction of OTA and CAP with their aptamers. The tails of the end of dumbbell hairpin sequence can induce the entropy driven catalytic reactions on the AuNPs, causing the sustained releasing of the fluorophore labeled DNA sequences. The recovery of fluorescent intensities can be used for quantitative detection of OTA and CAP. The limit of detection reached 2 pM for OTA and 6 pM for CAP respectively, which was great improved by entropy driven amplification of the self-powdered DNA motor. This strategy is simple and sensitive and only needs one-step operation. It exhibits promising potentiality in food quality control and food security supervision.

A “turn-on” and proximity ligation assay dependent DNA tweezer was proposed for one-step amplified fluorescent detection of DNA. Target DNA can anneal with capture probe to form an entire long sequence. The formed long sequence can circularly open the hairpin, resulting the “turn-on” of DNA tweezers. A good linear relationship was shown from 40 pM to 20 nM with limit of detection of 10 pM. In addition, it has been successfully utilized to analysis DNA in human serum, representing a great and practical application future.

Ketamine is a commonly abused drug due to its stimulant, dissociative and hallucinogenic effects. An overdose of ketamine has been found to cause a variety of side effects. Therefore, the identification and quantification of ketamine are of significant importance for clinical purposes and drug seizing. However, conventional methods for ketamine detection possess some disadvantages such as sophisticated procedures, expensive instruments and low sensitivity. Herein, we develop a novel fluorescent nanoprobe for ultrasensitive ketamine detection with signal amplification based on Adenosine Triphosphate (ATP)-fueled target recycling and FRET (fluorescence resonance energy transfer) occurring between the FAM (Fluorescein, tagged with Y-shape DNA) and AuNPs. Based on the combination of FRET and signals circle amplification, the gold nanospheres functionalized with Y-motif DNA (Y@AuNPs) nanoprobe was utilized for effective ketamine detection with the limit of detection (LOD) down to 3 pg mL⁻¹, which was lower than previously reported. Furthermore, the high sensitivity of Y@AuNPs facilitated quantitative analysis in biological media and practical samples.

The exploitation of multifunctional nanocomposites is highly desired in environmental monitoring, biosensors, and medical diagnosis. In this paper, a simple approach has been proposed to fabricate MoS2 decorated N-doped carbon nanotubes ([email protected]2) hybrid composites as efficient peroxidase-like mimics. The combination of the MoS2 and N-doped carbon nanotubes (NCNTs) brings about an enhanced synergistic effect, leading to remarkably decent intrinsic peroxidase-mimic activities than that of the single components. Due to the high catalytic efficiency of the resultant [email protected]2 hybrid nanotubes as peroxidase-like mimics, a convenient colorimetric approach for the sensitive determination of H2O2 and ascorbic acid have been developed with a detection limit of about 0.14 μmol/L and 0.12 μmol/L, respectively. The work offers a new strategy for the fabrication of peroxidase-like nanomaterials with excellent catalytic activity, which indicates great promising applications in sensitive detections in real samples.

An efficient strategy for growing thermo-sensitive polymers from the surface of exfoliated graphene oxide (GO) is reported in this article. GO sheets with hydroxyls and epoxy groups on the surface were first prepared by modified Hummer’s method. Epoxy groups on GO sheets can be easily modified through ring-opening reactions, involving nucleophilic attack by tris(hydroxymethyl) aminomethane (TRIS). The resulting GO-TRIS sheets became a more versatile precursor for next ring opening polymerization (ROP) of ethyl ethylene phosphate (EEP), leading to GO-TRIS/poly(ethyl ethylene phosphate) (GO-TRIS-PEEP) nanocomposite. The nanocomposite was characterized by 1H NMR, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), differential thermal gravity (DTG), transmission electron microscopy (TEM) and atomic force microscopy (AFM). Since hydrophilic PEEP chains make the composite separate into single layers through hydrogen bonding interaction, the dispersity of the functionalized GO sheets in water is significantly improved. Meanwhile, the aqueous dispersion of GO-TRIS-PEEP nanocomposite shows reversible temperature switching self-assembly and disassembly behavior. Such a smart graphene oxide-based hybrid material is promising for applications in the biomedical field.

Mesoporous silica-coated multi-branched gold nanoparticles ([email protected]2) aiming for enhanced Raman sensing for 4-bromomethcathinone (4-BMC) detection is reported. In this work, we present an effective strategy to probe the Raman signal of 4-MBC. Morphologies and optical properties of the synthesized materials with different [Au³⁺]/[Au⁰] ratios are characterized utilizing transmission electron microscopy (TEM), UV–vis and mid-infrared spectroscopy. Both experimental and theoretical (simulation) studies were investigated. Taking advantages of gold core branches that provide highly localized and strongly enhanced electromagnetic fields due to plasmon resonance, surface-enhanced Raman scattering (SERS) is observed. The experimental results show that the SERS intensity exhibits a 100-fold increase with the increased average length and quantity of gold branches (nano tips). The analytical performance yielded a detection limit of 0.1 mg/ml for the 4-MBC target within 5 mins. The sensing method will likely find further improvement and broad use in the forensic science. Besides rapid detection and portability, the combination of the Raman effect and enhanced materials imparts other notable advantages, such as its non-contact and free of reagents.